CICS / WebSphere

The CICS Data Sharing Servers

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After the AXM subsystem has started, z/OS ignores further attempts to do so. 

AXM modules are differentiated from traditional CICS modules by means of the three-character prefix ”AXM,” as opposed to the DFH-prefix assigned to other CICS modules. Likewise, AXM diagnostic and informational messages are prefixed by the letters AXM. As with DFH-prefixed CICS messages, this is followed by a two-letter identifier, which denotes the particular functional area of the AXM subsystem that issued the message. 

Along with various other CICS-supplied modules, AXM modules AXMSC and AXMSI are supplied in SDFHLINK and reside in an APF-authorized library in the z/OS linklist. AXMSC provides AXM server connection routines and AXMSI provides the AXM subsystem initialization function. 

Temporary Storage Pools  

Using temporary storage data sharing means replacing main or auxiliary storage destinations for temporary storage queues with one or more TS pools, where the scope and function of each TS pool is similar to that of a traditional QOR. Each TS pool is defined using z/OS Cross-System Extended Services (XES) as a keyed list structure in a coupling facility. TS pools are defined using CFRM policy statements. Using the CFRM policy definition utility, IXCMIAPU, specify the size of the list structures required, together with their placement in a coupling facility (see a sample definition statement in Figure 2). 

The name of the list structure for a TS pool is created by appending the TS pool name with the prefix DFHXQLS_. When a list structure is allocated, it can have an initial size and maximum size as specified in the CFRM policy. The CICS System Definition Guide contains information on calculating suitable structure sizing, based upon the expected storage requirements. IBM recommends using the CFSIZER tool for structure sizing calculations. Learn more at: www.ibm. com/servers/eserver/zseries/cfsizer/ index.html. 

Structure sizes are rounded up to the next multiple of 256K at allocation time. When defined, activate the CFRM policy using the z/OS operator command: 

SETXCF START 

If sufficient space is available in the coupling facility, a list structure can be dynamically expanded from its initial size toward its maximum size. It can also be contracted to free up coupling facility space for other purposes. If the initial structure allocation becomes full, the structure doesn’t automatically expand, even if the structure allocated is less than the specified maximum size. To expand a list structure when the allocation becomes full, it can be expanded (up to its maximum size), using the following SETXCF command: 

SETXCF START,ALTER,STRNAME=DFHXQLS_ 

6 Pages